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CVE Record

CVE-2026-26144: Microsoft Excel Information Disclosure Vulnerability

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-26144 is a Microsoft Excel information disclosure issue. Microsoft describes it as cross-site scripting caused by unsafe input handling during web page generation. An unauthenticated network attacker could disclose sensitive information. The provided sources list Microsoft 365 Apps for Enterprise version 16.0.1 as affected.

Executive priority

Treat this as high-priority Microsoft 365 patching. It is not confirmed as actively exploited in the provided sources, but the confidentiality impact is high and the vendor advisory indicates a patch is available.

Technical view

The issue is mapped to CWE-79 and scored CVSS 3.1 7.5: network reachable, low complexity, no privileges, no user interaction, unchanged scope, high confidentiality impact, no integrity or availability impact. Microsoft’s advisory is tagged as a patch source, but the bundle does not include fixed build details.

Likely exposure

Exposure appears limited to Microsoft 365 Apps for Enterprise version 16.0.1 based on the provided bundle. Organizations should verify deployed Microsoft 365 Apps channels and builds against MSRC guidance because the bundle does not enumerate all channels or fixed versions.

Exploitation context

The bundle does not show CISA KEV listing or public active exploitation. CVSS indicates theoretical remote unauthenticated exploitation without user interaction, but the public details provided do not describe the triggering workflow, vulnerable endpoint, or observed attacks.

Researcher notes

Public evidence is thin. The bundle names CWE-79 and an affected product/version, but not the precise vulnerable component, fixed build, proof of concept, or detection logic. Avoid assumptions and anchor validation to MSRC.

Mitigation direction

  • Review the Microsoft MSRC advisory for fixed builds and update instructions.
  • Update affected Microsoft 365 Apps for Enterprise deployments through supported Microsoft update channels.
  • Prioritize endpoints handling sensitive spreadsheets or high-value user accounts.
  • Restrict exposure to untrusted Excel-generated web content where operationally feasible.
  • Monitor Microsoft guidance for revisions to affected versions or mitigations.

Validation and detection

  • Inventory Microsoft 365 Apps for Enterprise versions across managed endpoints.
  • Compare installed builds with the MSRC advisory’s affected and fixed version guidance.
  • Confirm update compliance through endpoint management or Microsoft 365 Apps reporting.
  • Review security telemetry for unusual Excel-related network information disclosure patterns.
  • Document systems that cannot be updated and apply vendor-supported compensating controls.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-79: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-26144 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
1ADP providers
2Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C3.93.6microsoft

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-26144Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MicrosoftMicrosoft 365 Apps for Enterprise16.0.1Listed
Weakness

CWE details

CWE-79

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.